Abstract

Hydrogen removal can be accomplished via different steelmaking routes (VOD, ASEA, RH). Focus was givenon the first two technologies. As main differences between the systems based on a (multi)-plug equipped ladle,in VOD the vacuum chamber is obtained by coupling a roof with a tank, in ASEA plant–where electromagnetic melt stirring is also exploited - coupling occurs directly with the ladle, leading oftento a non perfect sealing. Moreover, VOD plant is able to perform under vacuum steel degassing treatmentat pressure values lower than usually reached in ASEA plant, and is also equipped with a oxygen lanceallowing to produce stainless steels with very low carbon and nitrogen content. The industrial needof achieving very low hydrogen contents for big ingots casting with an acceptable costs/benefits ratio calledfor a comparison between performances of different vacuum treatments strategies. A CSM numericaldegassing model was applied to 140 ton ladle conditions either after ASEA or VOD treatment.